Continue index_test.cpp and index.hpp development.
Initialize compare members during open. Required for btree_index which doesn't have construction arguments until open time.
Fix boo boos. Ready to start tests.
Change file_path() to path() where there is only a single path. Too hard to remember. Add test cases to open_all_new_test. Fix bugs and oversights detected by these test cases. open_all_new_test now passing.